Hey I've been considering the JB4 for quite a while now, and am trying to do more research before I pull the trigger. Reading around, I found this thread: http://www.e90post.com/forums/showthread.php?t=658292 where OP has described that even after JB4 his throttle feels "airy".

I'm wondering if any of you guys who have the JB4 feel the same way? My car is stock and JB4 will most likely be my first performance mod. I'm not sure if I plan on changing anything else in the new future since I purchased BMW's extended maintenance plan. What do you guys think? Is it worth it to get the JB4? I would like to take my car to the track one day...

About the reliability issues...I wouldn't touch an n54 without bmw warranty....but up to you...

The only problem with the warranty is that if your running mods the warranty is pretty much useless, yes you can take the JB4 off before taking it to BMW but uninstalling downpipes is another issue. On top that if the turbos go in my 335i the last people I want touching my car is my local BMW dealer, who are not even competent enough to install the Apine speaker kit. I much rather take money to someone like Darrenwoods than deal with BMW directly....Can you tell i'm just a tiny bit dissappinted by my experiences of my local BMW dealers ??

Oh there is nothing 'airy' but the throttle response in my car with JB4, it's a fab mod just go for it!!

You're better keeping the warranty money in your bank and save it up to pay for things yourself. The terms of these warranties are so poor, they are weighted in favour of the insurance company giving the warranty (even optional BMW warranty is insurance backed, just like 'warranties-r-us').

Chances are you'll come out on top, its just a gamble, but the odds must be in your favour otherwise the insurance co wouldn't make any profit.

But if you're planning on keeping warranty, you really need a decent code reader like a Bavarian Technic cable.

Unless you can be sure you've reset / deleted any codes before taking it in, you could leave yourself wide open to void warranty.

The JB4 will delete codes, but only when it's connected, you might activate some codes when removing the unit, and then you're stuck as you can't check if there are any codes.

You're better keeping the warranty money in your bank and save it up to pay for things yourself. The terms of these warranties are so poor, they are weighted in favour of the insurance company giving the warranty (even optional BMW warranty is insurance backed, just like 'warranties-r-us').

Chances are you'll come out on top, its just a gamble, but the odds must be in your favour otherwise the insurance co wouldn't make any profit.

But if you're planning on keeping warranty, you really need a decent code reader like a Bavarian Technic cable.

Unless you can be sure you've reset / deleted any codes before taking it in, you could leave yourself wide open to void warranty.

The JB4 will delete codes, but only when it's connected, you might activate some codes when removing the unit, and then you're stuck as you can't check if there are any codes.

Kind of makes sense, is that what you do? Have a slush fund for repairs?

You'll find the BMW insured warranty is worth it's weight in gold. If you have a problem and take it to the dealer, as long as it's not bodywork, trim, or seals, the dealer will try their damnest to get the work approved by the warranty company.
The dealer gets paid direct from the warranty company, and therefore the more work they can claim for the better.
I had both my turbo's replaced late last year under the warranty (which was just wastegate rattle) there were no issues making the claim, The dealer had the car for a week, they gave me a courtesey car to run around in, and the final bill would of cost me £3-4k.
Paid for itself on the first claim!

Would the warranty have covered my turbos given the fact I have Catless Downpipes, FMIC, Meth kit, Diverter valves etc? I dont think so. If the clutch went tomorrow, I'm sure they would say the same story, the clutch isnt designed to have 50% more power/torque running through it.

Would the warranty have covered my turbos given the fact I have Catless Downpipes, FMIC, Meth kit, Diverter valves etc? I dont think so. If the clutch went tomorrow, I'm sure they would say the same story, the clutch isnt designed to have 50% more power/torque running through it.

If you want a warranty, keep the car standard or just tune only.

if you plan to go further, then pocket the cash.

"You have to Pay to Play"

Like I say they wouldn't of made much money out of just adjusting/replacing wastegate actuator arms, so two new complete units it was!
You wouldn't take a car for a warranty claim with downpipes, intercooler etc.. fitted anyway, as I'm pretty sure it would void the warranty, and therefore be a waste of money.

I agree not worth taking on a warranty with mods.

What I am saying is the BMW insured warranty is very very good, and offers piece of mind for people who can't face huge bills for repairs.

Kind of makes sense, is that what you do? Have a slush fund for repairs?

My only concern is the HPFP and wastegates.

That's about it.

The HPFP is only about £250 to buy now I think, where it used to be about £750. The fitting would be a couple of hours at an indy. Mine failed still in the 3yr warranty so it was changed by BMW for free (suprisingly the car had the BMS DCI, lowered suspension, JB3, M3 strut brace and NO service history on the BMW system and they still fixed it)

Wastegates can just be adjusted for a long while to get rid of any rattle, but yes if they're knackered then they need to come off.

But you can get them fixed for £200 each by Turbo Dynamics and re fitted.

Unfortunately modding is a slippery slope, and when you get that JB4 that's just the start.... goodbye dealers...